Leveraging SPI-DMA for PROFINET Isochronous IRT Cyclic Communication

PROFINET IRT (Isochronous Real-Time) is a specialized communication protocol used in industrial automation to ensure high-speed, deterministic data transmission with minimal jitter. The ISO (Isochronous) mode within PROFINET IRT provides precise synchronization of data transmission cycles across communication components, ensuring optimized control and reliable timing, particularly in high-speed production environments and motion control applications. Typically, such systems integrate a PROFINET ASIC (Application-Specific Integrated Circuit), such as the ERTEC (Enhanced Real-Time Ethernet Controller), with a secondary MCU (Microcontroller Unit) to manage complex tasks while maintaining deterministic communication with minimal jitter, often within $1~\mu $ s. However, conventional communication interfaces like PCIe (Peripheral Component Interconnect Express) and XHIF (External Host Interface) introduce additional hardware and software complexity. This study presents a novel approach utilizing SPI (Serial Peripheral Interface) communication, enhanced with DMA (Direct Memory Access) hardware, for high-determinism applications within a PROFINET ISO IRT network. SPI, a synchronous communication protocol widely used in embedded systems, facilitates efficient data exchange between MCUs and peripheral devices. The proposed method demonstrates the performance of SPI-based communication between an ERTEC ASIC and a secondary MCU (STM32F401), applied in a real-world communication processor operating over PROFINET ISO IRT. This approach not only reduces hardware and software complexity but also enables the use of cost-effective MCUs as host controllers alongside PROFINET ASICs, thereby enhancing the scalability and affordability of industrial automation solutions.